Conventional fluid fracturing of subterranean formations comprises positioning a tool in a cased wellbore traversing a zone to be fractured. The tool straddles perforations in the cased wellbore. Fluid is pumped down a tubular conduit from surface to the subterranean tool at a flow rate and pressure sufficient to hydraulically fracture the formation.
The exact nature of the resulting fractures is not fully known and will vary for different formations. As set forth in U.S. Pat. No. 4,995,463 to Kramm et al., issued in 1991, the fracture mechanics and fluid flow behaviour in cleated, coal bed formations is substantially different that those in sandstone and the like which are more conventionally known for oil and gas operations.